Dog clutch



Doc: CLUTCH l 7 ,5. ..7 4M@ .w Ivy/4 llllll Jan. 9, 1962 O. MITCHELL v Filed Feb. 27, 1957 United States Patent 3,016,252 DOG CLUTCH Orville Mitchell, Dallas, Tex., assigner lto John E. Mitchell Company, Inc., Dallas, Tex., a corporation of Missouri Filed Feb. 27, 1957, Ser.No. 642,891

11 Claims. (Cl. 281-52) The present invention relates to a dog clutch. It has `particular application .to a clutch such `as that used on automobile Aair conditioner compressors wherein the driven Eclutch member is operated bya belt such as the fan belt `of -the automobile and the `concentric driven member -drives the `compressor shaft.

yInthe particular embodiment shown, the driving memlber rotates 'around 'the periphery of the driven member with an appropriate 'bearingbetween them. This specific relationship lis not essential to the inventive features hereof. The ydriving member carries a pair of pivoted clutch dog arms that Yare normally resiliently urged to Aforce their dog 'elements into engagement against oppositely facing abutmentl surfaces of 'the driven member, .in a predetermined vorder. The dogs and vthe abutment surfacesars so shaped, andtravel in such paths, that they engage with vawedgirtg action 'thatprecludes 'lost motion of'whichever member 'of the clutch is the driving member. v The dogs varms'can be latched in vtheir released positions, the latches 'being 'manuallyreleasable so that the clutch may been- 'gaged lor disengaged at will.

As noted, a particular usage o'f theinvention v1is on automobile air conditioner equipment because lit is desirable to be able to disconnect 'the air conditioner compressor during `cold weather, thereby to relieve its load from the engine, and to make a corresponding reduction in idling wear on the compressor. However, other uses will be apparent .from an understanding of the construction.

One of the particular features of this clutch is that ,it automatically locks itself tightly whenever the two dogs are released intotheir operation position, regardless of the order in which the dog arms are released. It not only locks tightly but it locks .itself against an ,irregularv order, the normal running of :the driving memberwill l' cause them to be Withdrawn and `tobe re-engaged in the proper order to produce `theftight, wedging'eifect.

VAnother object of the invention is -to provide, `in `a clutch ofpthe .foregoing kind, .a -construction such that the 'dogs may be lmanually released `withno trou-ble,when ever it is desired to 'release them. i

3,016,252 Patented Jan. 9, 1962 ICC The clutch includes an outer 4driving member 12 andv an inner driven member 13 upon which the outer niem- ;b`er1`12 rotates, with Aa suitable bearing 14 interposed between' them. It lis not necessary. hereto showl the details .of the connections lbetween these parts, since it is readily understandable how they can be supported for coaxial, relative rotation. f

The driving element is shown in the shape of a V- pulley so that it can receive a'V-belt 15, by means of which .it may lbe driven from some suitable .source of power such as the crankshaft of an automobile engine. The inner, driven'rneinber 13 of the clutch assembly is mounted upon the tapered end of the shaft 17 of a compresso'r' 18,"th`ere being an appropriate key 19 between them. The parts are secured together by va Vscrew and 'washer 21, all as is 'readily apparent from the drawing.

The driving member ispro'vided with two clutch dog arms 24 and 25 that are rockably pivoted at 26 Vand 27 respectively on what will be termedv the Aouter face of the driving' member. A fairly stiff'coil -spring 28 is connected between projections 29 and 30 on the ends of the dog arms 24 and 25.y The spring 2.8l urges the ends of the dog .arms towardeach other and ral'sotovva'rd the edge of adisc 31 `that is held Yby two screws 32 to the outer surface of the inner clutch element 13.v As will appear,

` this spring action urges *the clutch .dog` arms into coupling positions.

The dog arms .or -levers 24 and 25 have clutch dogs 35 A.and A36 .projectingtherefrom as illustrated in the drawings, so 'that they can Iimp'inge upon the peripheral edge of `the disc `3:1 .or can engage two adjacent ones of the notches 37a, 37b, 37C, and '37d in lthe peripheral edge ofthe disc 31. 'Each of the notches Vhas a forward .radial f end .edgex and a rearward"radia end edge y. Actually these edges x and y are parallel to a radius drawn through the Vmiddle of such notch. p

vThe dog35 on the dog arm k24 has a forward edge 40 merging in a bottom or inner edge 41 at a point or tip 42. YThe' edge 41 'then mergesinto an edge 43. The size of the dog 35 is sulicient that ywhen the forward edge 40 is `engagediagainst the Acorresponding edge x of any notch 37, the rear 'slopingedge 43 will 'rest upon the trailing corner ofthe edge y of the notch. In this position, which is the maximum distance that the dog '35 can enter any of Other objects will appear from-the :description to -follow.

In the --drawingsz FIGURE Vl is a front .elevation :ofthe-clutch and tits driving belt showing `the clutch -dogs engaged'infproper fashion to lock Vthe clutch;`

FIGURE 2 is va :side :elevation of the clutch Ashown in rFIGURE l, vshowing how git lis attached "-to a 'com-l pressor shaft, rand `with-the driving vbelt shown fragmentally'g- FIGURE T3 is a vertical section 'on 'the line 13--3 of FIGURE 1; A FIGURE 4 is a partial hsection taken on .the line 4-4 of FIGURE 1 tofsh'ow the dog arrn'latch released;

FIGURE 5 is a front elevation ofthe clutch Ywith :the

dogs retracted;

the slots,the 'forward edge 40 is approximately normal to ajfradius drawn to the bottom of the notch y37 from the ce'nter'ofthe pivot 26 'for fthe dog arm. The purpose of this is to be'sure that the dog arm may be pivoted in a direction to withdraw `the do'g from `the 'slot without having the tip 42'bind` against lthe'edg'elx.

Also, the sloping edge 43 at the back of the dog should have an angle such that, if tthe driving element 12 is ro tated backwardly relative to t-h'e driven element (which l camming .action ras-.Wille appear.

The contours of the edge y of the notch 37b and the abutment edge Si) of the dog 36, and the distancerfrom the abutment edge 50 to the pivot center 27, are such that, when the rst or main dog 35 is in its fully engaged position illustrated in FIGURE l, and the second or wedging dog 36 is approaching its engaging position, a wedging action occurs in which the dog 36 attempts to force the entire driven member backward against the resistance of the main dog. This is accomplished by having the angle between a radius from the center ofthe pivot 27, to the surface y of the notch at the point of contact less than 90 with that surface y. By this arrangement, further inward movement of the dog 36 wedges against the surface. While the edge contours may vary from those shown, the wedging relationship, Such as is obtained in these edges by that angular relationship, is of great importance to this invention. In simplest embodiment,v the edge y will be flat and substantially parallel to theradius through the middle of the notch, and the dog abutment edge 50 will be flat and parallel to that edge when the arm 25 disposes the point 52 ofthe dog 36 at the entrance to the notch 37b. When the dog is fully entered into the notch, the edge 5t? will have a slight slope toward the axis of the clutch.

The 'amount of displacement of the clutch member 13 produced by the dog 36 acting against the edge y is suhicient, so that if the dog 36 acts against the edge y when the main dog 35 is not in the notch 37a, the forward edge x of the notch 37a will be rearward of tip 42 of dog 35, as illustrated in FIGURE 7. This will prevent any engagement of the dog 35 in the notch 37a until the driving member 12 is forced forwardly 90 to bring another pair of notches adjacent the two dogs.

The dog 36 should be narrower across the base than the notches 37. This will insure full movement of the dog 36 into the slot, so that adequate wedging action can be had, even after wear on the parts, and without very small tolerances in machining of the parts in manufacture. The edge 53 of the dog 36 slopes outwardly and forwardly, with such angle that clockwise rotation of the outer clutch member 12, in the positions of FIGURE 7, will cam the dog out of the notch.

The two dog arms may be held in retracted position. To this end there are two push buttons 60 and 61, supported in the dogs. Their construction is identical and only one need be described. As shown in FIGURES 4 land 6 the push button 6G is flanged on its inner end and is slidably inserted in a hole 62 through the dog arm 24,

There is a bore 64 in the driving member 12 which receives a coil spring 65 that acts upon a slidable cap 66.

Whenthe cap 66 is aligned with the hole 62 and the push button 66, the spring 65 will push the cap member 66 into the hole 62 against the push button 69, and force the push button outwardly. The cap thereby locks the dog arm in the position illustrated in FIGURE 5. Finger pressure upon each of the push buttons 60 land 61 forces the caps 66 inwardly against their springs 65 until the iianges of 6i? and 61 strike the surface of the member 12, whereupon spring 2S will draw the two dog arms toward each other.

Operation A particular use of the clutch of this invention is to connect and disconnect the compressor of an automobile air conditioning system from the automobile engine, so that the compressor is not driven at times when air conditioning is not needed.

A compressor provides a pulsating load on the clutch, resulting from the fact that when the compressor crankshaft goes over dead center, the compressed gas in the cylinder tends to surge the piston forwardly, causing the driven member to become the driving member of the clutch. As a result, any lost motion in the coupling,

4 whether in forward or reverse direction, will cause objectionable noise, Wear, and other problems.

The present clutch is shown fully released in FIGURE 5. The outer clutch element 12 is designed to rotate clockwise and to drive the inner element 13 upon which the disc 3@ is mounted. In order to couple the clutch elements, the user merely depresses the buttons 60 and 61 as far as they can go, whereupon the push button latch elements 66 lare retracted and the spring 28 can draw the upper ends of the two dog arms 24 and 25 toward the periphery of the disc 30.

The lower part of each of the dog arms is sufficiently wide that it continues to cover the ends of its cap 66 when the dog arm is in its inward coupling position.

With the outer clutch member 12 rotating clockwise, the dog arms released, and the dogs 35 and 36 riding on the periphery of the disc 36, the dog 35 will enter the notch 37a before the tip 52 on the dog 36 has reached the edge y of the notch 37b. The dog 35 will almost reach the position of FIGURE 1 before the dog 36 is permitted to enter the notch 37b. However, just at the time when the surface 40 on the dog 35 is ready to make contact against the edge x of the notch 37a, the corner 52 of the dog 36 will drop vinto the notch 37b and its edge 56 will wedge against the edge y of the vnotch 37b, as heretofore explained, in such wise as to produce a tight forced engagement between both dogs and their notches.

The upper edge 40 of the dog 35, acting against the notch edge x, constitutes the abutment edge for driving the clutch in the forward direction, While the edge 50 of the dog 36 acting against the notch edge y, constitutes the 'abutment edge for transmitting any driving thrusts when the driven element becomes the driving element.

The foregoing wedging action is the thing that insures that there will be a solid drive with no lost motion, even with a pulsating load.

It can be noted from the foregoing that the wedging action is obtained only when the dog 35 engages its notch first. But the clutch is `designed so that, even if the dogs I35 and 36 do not enter the notches 37a and 37b in that order, they, nevertheless, will readjust themselves to the proper order automatically.

If the button 61 is operated to release the arm 25 while the clutch members happen to be positioned so that the dog 36 enters the notch 37b, as illustrated in FIG- URE 7, then the edge 50 of the dog 36 quickly abuts the upper edge of the notch 37b. When this occurs, the dog 36 is all the way into the notch 37b, which displaces the clutch members so that the dog 35 cannot enter the notch 37a at all. FIGURE 7 illustrates this relationship. However, a continued clockwise driving movement of the clutch member 12 will cause the yarm 25 to be drawn d clockwise, and the dogs slanting surface 53 to engage the the do-g 36 can reach the subsequent notch 37C. The

coupling then proceeds normally to obtain the wedging effect.

When it is desired to uncouple the clutch, as when air-v conditioning of the vehicle is no longer desired, the operator merely engages the lower ends of the two arms 24 and 25, which are long enough to provide handles with adequate leverage to make it convenient to spread the upper ends of the two levers. The lower ends of the arms 24 and 25 are squeezed together until the caps 66 under the push buttons 60 and 61 latch in place within the push button holes 62, after which the arms cannot be re-swiveled to their clutch engaging positions -without depression of the two push buttons.

The withdrawal of the arms is facilitated by the geometry previously described. In order to assure good wedging action, the movement of the dogs toward the axis, is always accompanied by wedging drives against l the notches. This same geometry means tha-t, asrthe dogs move out of the notches, their'resp'ective .abutment edges simultaneously backaway'from their corresponding notch edges.

It is,`of course, understood that variations ofthe clutch may be made, without departing from use of the present invention.

What is claimed is:

1. A clutch having first and second rotary clutch members, each rotatable relative to the other, one of which is a driving member and the other of which is a driven member; first and second clutch dogs, means supporting the dogs in spaced relation on the first member for movement toward and from the second member, in predetermined, fixed paths; means defining recesses in the second member into which the dogs may engage; means associated with the dogs for resiliently urging the dogs into the recesses; releasable means engageable by the dogs for holding the dogs out of the recesses; means including interoperating slidably engageable portions of the dogs and the recess walls to cause the dogs to wedge into engagement with oppositely facing walls of the recesses when the first d-og enters a recess first, and the second dog thereafter enters a recess, and means including differently sized lbase portions of the respective dogs to insu-re that the dogs will ultimately engage the recesses in that order upon release of the releasable means, regardless of which dog initially enters a recess first.

2. A clutch having first and second rotary members, each rotatable relative to the other, one of which is a driving member and the other a driven member; the first` member `having a pair of clutch dogs connected to it in such a way as to be movable in and out ltoward and from the axis of the clutch and the second member having a pair of generally radial abutment surfaces against which the dogs may respectively engage when so moved, one surface being disposed in the' forward direction of rotation from its dog and the other surface being disposed in the backward direction of rotation from its dog; so that when the dogs are engaged with their respective surface they provide driving engagement between the clutch members in both directions of rotation, one of the dogs being la main dog and the other being a wedging dog having means to cause a-ngular displacement between the rotary members, so that it can force the other abutment surface tightly against the main dog.

3. The combination of claim 2, wherein the abutment surface engaged Iby the wedging dog is of sufficient radi-al extent that when its dog is in fully moved engaged position, it will have displaced theother abutment surface too far to permit the main dog to move into engagement therewith.

4. The clutch of claim 3, wherein the wedging dog has a follower surface adjoining its part engaging the abutment surface, said `fol-lower surface being formed so as to slope in the direction of `forward rotation from the abutment surface and away from the member having the abutment surfaces, whereby if the sloping surface is forced against the abutment surface for the other dog, it will be cammed outwardly therefrom.

5. The clutch of claim 3, with resilient means urging the dogs toward clutching engagement, the second clutch member having a circular portion notched in itsedge to provide the abutment surfaces, and thev main dog having a lower surface that extends in the direction of backward rotation and away from the second clutch member, so that when it is urged toward clutching engagement during rotation of the driving member, it will move into the notch and then into engagement with its yabutment surface; and

the wedging dog can engage in its 4recess only after the main dog has at least substantially reached its abutment surface.

6. The clutch of claim 2, wherein there are two arms, one supporting each dog, lboth arms being pivoted onto the first clutch member, resilient means urging the arms toward clutching; position, and releasable ,latch means for holding the arms in clutch-disengaging position.

7. rIlhe 'clutch'ofclaim '6, vwherein the arms are pivoted about axes lparallel lto lthe 'clutch axis, and the abutment surfaces Iare, disposed substantially. perpendicular to 'radii from the'pivot axes, and theitips of the dogs engaging the abutment surfaces, when the dogs are both engaged,

are not moved further toward the clutch axis than the radii from the pivot axes that are perpendicular to the abutment surfaces.

8. A clutch having first and second rotary clutch members, eac-l1 rotatable relativeto the other, first and second dog members movably mounted on said first clutch member, meansV defining two oppositely angularly faced surfaces on said second clutch member, resilient means operative upon the dog members for urging said dog members simultaneously toward `said second clutch member for respective Iabutting engagement with the oppositely angularly faced surfaces, and means including additional interengageable elements on the first dog and on the second clutch member for insuring ultimate engagement of the second dog with its one of said surfaces Subsequently to engagement of said first dog with another of said surfaces.

9. The combination of claim 8 wherein the oppositely angularly faced surfaces comprise portions of identical notches disposed equal radial distances from the axis of rotation of the second clutch member, and wherein the dog members are differently formed so as to be restricted I to different limits of engagement in said notches.

' with its one of thesurfaces subsequently to engagement of the first dog with another of the surfaces.

ll. A clutch having first and second rotary clutch members, said second clutch mem-ber being rotatable relative to the first one under one condition of the clutch, means defining two oppositely angularly faced surfaces on said first clutch member, first and second dog members movably mounted on said second clutch member, said dog members being mounted for movement in respective predetermined paths toward respective ones of said surfaces, the path of movement of the first dog member being such as'to enable the first dog member to move into a position for abutment with its one of said Surfaces, when the second clutch member is rotated relative to the first, the path of movement of the second dog member being such as to provide 4slidable biasing engagement between the second `dog member and its one of said surfaces so as to urge the first clutch member toward rotation in a direction to move the other of said surfaces toward and beyond a position for abutment with the first dog member, and

resilient means `operable upon the dog members for simultaneously biasing the first dog member toward its aforesaid position for abutment and the second dog member toward slidable biasing engagement with its one of said from moving into abutment with its aforesaid surface while the second dog member is in biasing engagement with its surface.

References Cited in the file of this patent UNITED STATES PATENTS 697,166 Phelps et al.` Apr.8, 1902 `(Other references on foliowing page) 7 UNITED STATES PATENTS Musser Oct. 26, 1909 Boda Dec. 7, 1909 Evensen Dec. 14, 1915 Purssell Aug. 8, 1916 5 Geldhof Oct. 6, 1936 S Fischer June 27, 1939 Crosmn Feb. 5, 1946 Malone et al. Ian.'14, 1947 Meyer June 14, 1949 Gardiner et a1. f Apr. 7, 1953 

